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Full text of "The manufacture and properties of iron and steel"

INTRODUCTION.                                             25
is subject to vibration and shock, and that in such open-hearth steel the phosphorus should be lower than in the ordinary run of Bessemer steel. In some other matters they do not agree. They differ in regard to acid and basic steel. It is my opinion that acid steel, other things being equal, is superior to. basic steel, but the manufacturers, being unable to give an authoritative opinion, leave the .matter open to the engineer, stating what the phosphorus shall be in each case. This whole subject of specifications is now under consideration by the engineering societies of our country and especially by the American Society for Testing Materials, No ordinary specification, however, can take account of all the variations in the physical results from bars of different section, but certain laws must be recognized by the engineer and the manufacturer. These laws may be stated as follows:
(1)   In rounds an increase in diameter is accompanied by a decrease in ultimate strength, a greater decrease in elastic limit, an increase in the elongation, and a decrease in the reduction of area.
(2)  In angles an increase in thickness is accompanied by a decrease in ultimate strength, a greater decrease in the elastic limit, and a decrease in the reduction of area, while the elongation remains constant.
(3)  In plates a thickness of f inch to -J inch should be taken as the basis.
Thinner plates will show higher tensile strength, much higher elastic limit, lower elongation and lower reduction of area.
Thicker plates will show lower ultimate strength, much lower elastic limit, lower elongation and lower reduction of area.
Narrow plates will give higher elongation and higher reduction of area than wide plates.
Tests cut crosswise of the steel will usually show lower ultimate strength, lower elastic limit, lower elongation and lower reduction of area. This is most marked in long, narrow plates.
"Universal mill plates will show a greater difference between lengthwise and crosswise tests than will be found in sheared plates.
(4)  In channels, beams and similar sections, the tests cut from the web will follow the laws just stated for plates of medium width. In pieces cut from the flanges there will be a lower ultimate strength, a lower elastic limit, and a lower reduction of area.
(5)   In eye-bars, an increase in thickness will show a lower ulti-